Phenolic content and antioxidant activity of extracts of 12 melon (Cucumis melo) peel powders prepared from commercial melons

Authors: GANJI, SHIRIN MAL - California Polytechnic State University; SINGH, HARMIT - California Polytechnic State University; Friedman, Mendel

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/2/2019
Publication Date: 6/18/2019
Citation: Ganji, S., Singh, H., Friedman, M. 2019. Phenolic content and antioxidant activity of extracts of 12 melon (Cucumis melo) peel powders prepared from commercial melons. Journal of Food Science. 84(7):1943-1948. https://doi.org/10.1111/1750-3841.14666.
DOI: https://doi.org/10.1111/1750-3841.14666

Interpretive Summary: General interest in peels from fruits and vegetables considered to be waste products produced during food processing arises from the fact that many of them are reported to contain nutrients and bioactive compounds that have the potential to improve animal and human health. Utilizing such peel products can therefore lead to the potential development of health-promoting food supplements as well as alleviating waste from the food industry. The objectives of the present study were (a) to determine the total phenolic content and antioxidant activities of extracts of peel powders prepared from 12 Mexican and Honduran nonorganic and organic melons obtained from retail stores in California; (b) to determine the individual phenolic and flavonoid content of two melon peels and the flesh from three melons; and (c) to recommend melons with high antioxidant activity and high content of phenolic and flavonoid compounds for the further study of the their health-promoting potential. Our analysis of peel powders (prepared by peeling whole melons, freeze-drying the peels, and then grinding the dry peels to fine powders) of 12 different varieties of melon showed that, of these, organic Galia melon peel originating from Honduras, has the greatest phenolic content and antioxidant activity. The identified bioactive compounds and the high antioxidant activity suggests that this melon variety is a biosource of health-promoting phenolic and flavonoid compounds and natural antioxidants. Related studies on the reported composition, health benefits, beneficial effects in poultry, lamb and fish diets, and as renewable green substrates for the production of methane, and suggestions for further research are discussed

Technical Abstract: Melons are a diverse group of fresh, dessert fruits that includes orange flesh cantaloupe, green flesh honeydew, and mixed hybrid melons. As part of an effort to discover potential health benefits of fruit and vegetable peels that are considered to be byproducts of food processing, we determined the total phenolic content and antioxidative activities of methanolic extracts of the powdered peels of the following commercial melon (Cucumis melo) varieties sold at retail markets in California that were imported from Mexico and Honduras: nonorganic Canary, Charentias, Hani Gold, Vine ripened, and Santa Claus; and organic Ambrosia, Cantaloupe, Galia, Goddess, Ham, Honeydew, and Tuscan. The total phenolic content (in mg gallic acid equivalents/g extract) ranged from 0.69 (Tuscan) to 2.96 (Galia) or 4.3-fold variation from lowest to highest value. The antioxidative activity (in mg ascorbic acid equivalents/mL extract ranged from 0.13 (organic Tuscan) to 0.26 (organic Galia). Similar results were observed using the ABTS antioxidative assay. The content of the phenolic and flavonoid compounds 3-hydroxybenzoic acid, chlorogenic acid, neochlorogenic acid, isovanillic acid, apigenin-7-a-glucoside, luteolin-7-o-glucoside, and quercetin-3-galactoside in three melon flesh samples (nonorganic and organic Galia from Honduras and organic Galia from Mexico and two peel samples (Mexican organic peel and flesh) were analyzed using HPLC. The results suggest that the peel from the Honduran Galia melon with the highest antioxidative activity merits further study to investigate potential health properties. Potential nutritional and health benefits of melon peels, seeds and their bioactive compounds are discussed.